A group of scientists has discovered why stress causes gray hair to grow. Research can lead to new forms of treatment that go beyond traditional hair dye.
In the study published Wednesday in Nature magazine, a team of researchers, led by Ya-Chieh Hsu, a specialist in regenerative biology at Harvard University, demonstrates that stress causes damage to pigment regenerating stem cells in hair follicles.
As stress can be considered a form of accelerated aging, the results of the study may increase the hope of treating those who have problems, contributing to slow or stop aging. More important, explains the newspaper "The Guardian", can also help to understand how aging depletes stem cells and point out new ways for anti-aging therapies.
First animal tests
The fact that stress affects the entire body, and not just the capillary region, made scientists start by trying to understand which of the systems worked on hair color. Initially, the researchers believed it could be an immune system reaction. Thus, they removed the adrenal gland, responsible for the production of the hormone cortisol, of rats. However, the animals continued to show gray hair when subjected to stressful situations.
After having ruled out other possibilities, the team came to the conclusion that the problem was related to the nervous system, particularly the sympathetic nervous system, also called by some scientists as cranial nervous system. When faced with stressful situations, these nerves release norepinephrine, which is then absorbed by pigment regenerating stem cells.
From there, they found that stem cells act as a kind of reservoir for pigment cells. Over the years, with hair growth, stem cells become pigment-producing cells.
Norepinephrine, activated when we are in stressful situations, contributes to an excessive activation of stem cells, causing a total conversion to pigment cells, thus draining the reservoir prematurely.
Promising data for future studies
"When we started the investigation, my expectation was that the stress would be negative for the body, but what we found is that it goes beyond what was imagined", explains Ya-Chieh Hsu. "In a few days, all the pigment regenerating stem cells were lost. After they are lost, the pigment is not regenerated again. The damage is permanent", he says.
The discovery thus leaves an open door for future studies related to how stress affects other organs or tissues in the body. "Our discovery, made in mice, is just the beginning of a long road to better understand what happens in people," the scientist said in statements to the BBC.